The Bravia TV maker's shares rose as much as 6.9 percent in Tokyo after the report. The company declined to comment.

Sony, which last year sold its chemical business to the government fund, Innovation Network Corp of Japan (INCJ), for $700 million, is trying to revive the fortunes of its consumer electronics business by focusing on cameras, gaming and mobile devices.

Sony's CEO, Kazuo Hirai, speaking at the CES consumer electronics show in Las Vegas this month, said any unit not contributing to those core divisions or helping to end losses in televisions could be sold. Under the company's accounting rules, asset sales are booked as operating profit.

The INCJ has offered to invest in any firm created by merging Sony's battery division with the Nissan-NEC venture, the Yomiuri said. It is also looking for other potential Japanese buyers, the paper added, citing unidentified sources familiar with the matter.

Founded as a joint venture with Union Carbide Corp in 1975 and later made a fully-owned unit, Sony Energy Devices Corp was a pioneer in making lithium-ion batteries for computers and mobile devices.

Sony, however, which decided not to enter the more lucrative business for automotive batteries, has struggled against price-cutting South Korean rivals in a market worth $18 billion a year. The unit, which has three factories in Japan and two overseas assembly plants in China and Singapore, has assets valued by Sony at $578 million.